Scoping Review of Existing Evaluations of Smokeless Tobacco Control Policies: What Is Known About Countries Covered, Level of Jurisdictions, Target Groups Studied, and Instruments Evaluated?

OBJECTIVE: The implementation of smokeless tobacco control policies lags behind those for smoking. This scoping review summarizes the studies that evaluated public policies on smokeless tobacco regulation (SLT) and provides an overview of the jurisdictional level, target groups, and policy instruments. METHODS: Seven databases were systematically searched for studies reporting on public policies regulating SLT. Two reviewers independently screened all studies. Data extraction was performed using a predefined extraction form. Extraction was replicated for 10% of the identified studies for quality assurance. A narrative synthesis of the included studies was used to analyze and interpret the data. The protocol was published beforehand with the Open Science Foundation (OSF). RESULTS: Fourty articles comprising 41 studies were included. Most of the studies reported in the articles were conducted in the United States (n = 17) or India (n = 14). Most studies reported outcomes for students (n = 8), retailers/sellers (n = 8), and users/former users (n = 5). The impact of public policies on smokeless tobacco use, in general, was most frequently assessed (n = 9), followed by the impact of taxes (n = 7), product bans (n = 6), sales/advertising bans near educational institutions (n = 4), and health warnings (n = 3) on consumer behavior. CONCLUSIONS: There are significant gaps in the evaluation of smokeless tobacco regulation studies that need to be filled by further research to understand the observed outcomes. WHO reporting on Framework Convention on Tobacco Control (FCTC) implementation should be linked to studies evaluating smokeless tobacco control measures at all levels of jurisdictions and in countries not members of the WHO FCTC or do not provide data. IMPLICATION: Large gaps in the evaluation of SLT control policies exist. For some countries, WHO FCTC evaluations are available for different levels of jurisdictions. In countries with a strong federal structure, there is a lack of data beyond the national level to provide a more detailed look at compliance, indirect effects, or implementation gaps. More research is needed at all levels of jurisdictions, which add to the work of the WHO to understand what works for which target group, how the different levels of jurisdiction interact, how the real-world context can be incorporated, and what indirect effects may occur.

Effect of smoke-free policies in military settings on tobacco smoke exposure and smoking behaviour: a systematic review.

INTRODUCTION: Smoke-free legislation has been instrumental in reducing secondhand smoke (SHS) exposure in public places. However, the evidence of the impact of institutional smoke-free policies in settings such as healthcare and defence is weaker. Specifically, the literature on the effect of smoke-free policies in military settings has not yet been synthesised. METHODS: This review aimed to identify, critically appraise and synthesise the available evidence to evaluate the effect of defence smoke-free policies on SHS exposure. Eight electronic databases (eg, EMBASE, MEDLINE) were searched from inception to June 2020. We included English-language studies on smoke-free policies introduced in a defence setting, assessing their impact on SHS exposure (primary outcome) and healthcare utilisation, smoking behaviours and defence efficiency (secondary outcomes). Risk of bias was assessed using ROBINS-I. Synthesis without meta-analysis was conducted using vote counting of direction of effect. RESULTS: The search retrieved 4503 citations of which eight met inclusion criteria; two controlled and six uncontrolled before-and-after studies. The evidence, although low-quality, from one study indicated reduced SHS exposure following the introduction of a defence smoke-free policy. For secondary outcomes the review found mixed results, with the quit rate being the one outcome favouring smoke-free policies. The cumulative confidence of evidence is uncertain and therefore reliable conclusions cannot be drawn from these studies. CONCLUSIONS: A research gap exists for high-quality studies on the impact of defence smoke-free policies which should use comparators and, if possible, randomisation. Policy-makers should introduce institutional smoke-free policies in defence settings within an evaluative framework to generate such evidence.

Diurnal variability of fine-particulate pollution concentrations: data from 14 low- and middle-income countries.

BACKGROUND: Scientific understanding of indoor air pollution is predominately based on research carried out in cities in high-income countries (HICs). Less is known about how pollutant concentrations change over the course of a typical day in cities in low- and middle-income countries (LMICs).OBJECTIVE: To understand how concentrations of fine particulate matter smaller than 2.5 microns in diameter (PM2.5) change over the course of the day outdoors (across a range of countries) and indoors (using measurements from Dhaka, Bangladesh).DESIGN: Data on PM2.5 concentrations were gathered from 779 households in Dhaka as part of the MCLASS II (Muslim Communities Learning About Second-hand Smoke in Bangladesh) project, and compared to outdoor PM2.5 concentrations to determine the temporal variation in exposure to air pollution. Hourly PM2.5 data from 23 cities in 14 LMICs, as well as London (UK), Paris (France) and New York (NY, USA), were extracted from publicly available sources for comparison.RESULTS: PM2.5 in homes in Dhaka demonstrated a similar temporal pattern to outdoor measurements, with greater concentrations at night than in the afternoon. This pattern was also evident in 19 of 23 LMIC cities.CONCLUSION: PM2.5 concentrations are greater at night than during the afternoon in homes in Dhaka. Diurnal variations in PM2.5 in LMICs is substantial and greater than in London, Paris or New York. This has implications for public health community approaches to health effects of air pollution in LMICs.

Involving mosques in health promotion programmes: a qualitative exploration of the MCLASS intervention on smoking in the home.

Second-hand smoke (SHS) exposure is high among UK Bangladeshi and Pakistani populations, reflecting higher male smoking prevalence and fewer home smoking restrictions than the general population. The Muslim Communities Learning About Second-hand Smoke (MCLASS) study explored the feasibility and acceptability of implementing SHS education in 14 UK mosques. Religious teachers (RTs) in seven intervention mosques were trained and provided with a culturally appropriate educational package. After the intervention, mosque leaders, RTs and congregants' experiences and perceptions of the intervention were explored through interviews and focus group discussions. Delivery of the intervention varied across mosques. Facilitators and barriers included: mosque diversity (congregation size, organizational structure, educational activities, women's role and involvement); degree of trust between researchers and personnel; and views on SHS. Most participants thought mosques' involvement in SHS health promotion was appropriate, but the perceived importance of SHS differed. We found that a health promotion programme delivered within Islamic religious settings that engages RTs in the process of facilitation, can be acceptable and feasible, but care must be taken to explore the culture and ethos of the institution, including its organizational structure, management committee, RTs and congregation.

Predictors of cessation in smokers suspected of TB: Secondary analysis of data from a cluster randomized controlled trial.

BACKGROUND: Smoking cessation services are rarely found within health services in low income countries. Given the interactions between Tuberculosis (TB) and tobacco, including cessation support within TB programs offers a promising cost-effective solution. We conducted secondary analysis of data from a cluster randomized controlled trial of smoking cessation in health centers in Pakistan to identify predictors of continuous and short-term abstinence in smokers suspected of TB using cigarettes or hookah. METHODS: Predictor variables of those continuously abstinent at 5 and 25 weeks post quit-date (continuous abstinence) and those abstinent only at 5 weeks (short-term abstinence) were compared with those who continued smoking and with each other. Self-reported abstinence at both time points was confirmed biochemically. RESULTS: Data obtained from 1955 trial participants were analyzed. The factors that predicted continued smoking when compared to continuous abstinence were: being older RR 0.97 (0.95 to 0.98), smoking higher quantities of tobacco RR 0.975 (0.97 to 0.98) and sharing a workplace with other smokers RR 0.88 (0.77 to 0.99). Those with a confirmed TB diagnosis were more likely to remain continuously abstinent than those without RR 1.27 (1.10-1.47). CONCLUSIONS: Those diagnosed with TB are more likely to be abstinent than those diagnosed with other respiratory conditions. Beyond this, predictors of continued smoking in Pakistan are similar to those in high income contexts. Taking advantage of the 'teachable moment' that a TB diagnosis provides is an efficient means for resource-poor TB programs in low income settings to increase tobacco cessation and improve health outcomes.

Second-hand smoke and the risk of tuberculosis: a systematic review and a meta-analysis.

There is limited evidence and lack of consensus whether second-hand smoke (SHS) increases risk of tuberculosis (TB), which has substantial implications for unrestricted smoking indoors and TB control policies. We aimed to establish the association between SHS and the risk of acquiring and worsening of TB in non-smokers. We identified 428 articles in the initial search and 12 comparative epidemiological studies met our inclusion criteria. Exposure to SHS was found to have a higher risk of TB infection [risk ratio (RR) 1·19, 95% confidence interval (CI) 0·90-1·57] compared to non-exposure; however, this did not reach statistical significance. There was marked variability (I 2 = 74%, P = 0·0008) between studies' results, which could be explained by the differences in the diagnostic criteria used. Exposure to SHS was found to be statistically significantly associated (RR 1·59, 95% CI 1·11-2·27) with the risk of TB disease. There was significant heterogeneity (I 2 = 77%, P = 0·0006) between studies' results, which was sourced to the internal characteristics of the studies rather than combining different study designs. We did not find any studies for SHS and TB treatment-related outcomes. Thus, we conclude that SHS exposure may increase the risk of acquiring TB infection and progression to TB disease; however, the evidence remains scanty and weak.

Tuberculosis patients learning about second-hand smoke (TBLASS): results of a pilot randomised controlled trial.

BACKGROUND: Passive smoking is associated with tuberculosis (TB). Measures are required to protect non-smoking TB patients from second-hand smoke (SHS). SETTING: We developed a behavioural intervention to encourage TB patients to implement smoking restrictions at home in Pakistan. OBJECTIVES: To assess the likelihood of such an intervention being successful and to inform a definitive trial in future. DESIGN: This was a pilot randomised controlled trial in which non-smoking TB patients were randomised to receive either individual-based support or individual-based support combined with family reminders. We recruited patients living with at least one smoker in their homes. Our primary outcome was urinary cotinine level as a measure of SHS exposure 2 months post-randomisation. RESULTS: Of 273 patients assessed for eligibility, 150 (56%) patients were recruited and all but one were retained throughout the trial. A statistically significant absolute reduction was observed in non-smoking participants' exposure to SHS based on urinary cotinine levels in both Arm 1 (71%, 95%CI 61-79) and Arm 2 (76%, 95%CI 67-83) between baseline and follow-up at 2 months. CONCLUSIONS: The recruitment and retention rates for trial participants make it feasible to conduct a definitive trial in future. The observed effect size makes it worthwhile to conduct such a trial.

Tuberculosis in women from Pashtun region: an ecological study in Pakistan.

SUMMARY In general, tuberculosis (TB) is more common in men than women. However, for reasons currently not understood, women are 1.5-2 times more likely to report TB compared to men in Pashtun region (Afghanistan, adjacent provinces Pakistan and Iran). We explored whether or not gender disparity in TB notifications in the Pashtun region of Pakistan can be explained by Pashtun ethnicity. Using an ecological linear regression design, we estimated the effect of Pashtun ethnicity on female-to-male ratio (FMR) in TB notifications after adjusting for other determinants of women's health, in Pakistan. Districts with a high proportion of women of Pashtun ethnicity had a 44% (95% confidence interval 27-61) increase in FMR of notified TB cases compared to those with low proportions, after controlling for confounders. Genetic predisposition and distinct socio-cultural determinants could be possible causative factors. However, these hypotheses need further evaluation through rigorous longitudinal studies.

Smokeless tobacco consumption in a multi-ethnic community in Pakistan: a cross-sectional study.

Smokeless tobacco is commonly used in south Asia. In addition to causing oral and pharyngeal cancers, its harmful effects are comparable to smoking tobacco. A cross-sectional survey with systematic sampling was conducted in 2010-2011 to investigate smokeless tobacco use in a multi-ethnic, semi-urban population in Islamabad, Pakistan (n = 2030). The prevalence of smokeless tobacco use was 16.0% (21.6% among males and 8.8% among females); 51.7% of smokeless tobacco users were also cigarette smokers. The rate of smokeless tobacco use was comparatively high among Pakhtun males (38.2%) and Sindhi females (22.4%). The associations between smokeless tobacco use and ethnicity, age group, income level and cigarette smoking were statistically significant among male smokeless tobacco users. Of the sample 41.4% (840/2030) had inadequate knowledge about the health problems associated with smokeless tobacco. Appropriate interventions are needed to raise awareness of the health risks and to prevent smokeless tobacco use.

Smokeless tobacco consumption in a multi-ethnic community in Pakistan: a cross-sectional study

يشيع استخدام التبغ بدون تدخين في جنوب آسيا. وهو بالإضافة إلى أنه يسبب سرطان الفم والبلعوم، فإن آثاره الضارة يمكن مقارنتها مع تعاطي التبغ بالتدخين. وقد أجرى الباحثون دراسة مستعرضة بأخذ عينات منهجية في العامين 2010 - 2011 لمعرفة مدى استخدام التبغ بدون تدخين في مجموعة سكانية شبه حضرية ومتعددة الإثنيات في إسلام آباد، باكستان، وبلغ عدد العينات 2030 عينة. واتضح للباحثين أن معدل انتشار استخدام التبغ بدون تدخين قد بلغ 16.0% [21.6% بين الذكور و 8.8 % بين الإناث]، كما أن 51.7 % ممن يستخدم التبغ بدون تدخين كانوا يدخنون السجائر. وقد كان معدل استخدام التبغ بدون تدخين مرتفعا لدى ذكور باختون [38.2 %]، ولدى إناث السند [22.4 %]مقارنة مع غيرهم. وقد كان هناك ترابط يعتد به إحصائيا بين استخدام التبغ بدون تدخين وبين الإثنية، والفئة العمرية، ومستوى الدخل، وتدخين السجائر وذلك بين من يستخدم التبغ بدون تدخين من الذكور. وكان 41.4 % من العينة [840 فردا من بين 2030 فردا]لا يمتلكون معارف كافية عن المشكلات الصحية التي تترابط مع استخدام التبغ بدون تدخين. وتمس الحاجة إلى تدخلات ملائمة لرفع مستوى الوعي حول المخاطر الصحية وللوقاية من استخدام التبغ بدون تدخين

ABSTRACT Smokeless tobacco is commonly used in south Asia. In addition to causing oral and pharyngeal cancers, its harmful effects are comparable to smoking tobacco. A cross-sectional survey with systematic sampling was conducted in 2010–2011 to investigate smokeless tobacco use in a multi-ethnic, semi-urban population in Islamabad, Pakistan (n = 2030). The prevalence of smokeless tobacco use was 16.0% (21.6% among males and 8.8% among females); 51.7% of smokeless tobacco users were also cigarette smokers. The rate of smokeless tobacco use was comparatively high among Pakhtun males (38.2%) and Sindhi females (22.4%). The associations between smokeless tobacco use and ethnicity, age group, income level and cigarette smoking were statistically significant among male smokeless tobacco users. Of the sample 41.4% (840/2030) had inadequate knowledge about the health problems associated with smokeless tobacco. Appropriate interventions are needed to raise awareness of the health risks and to prevent smokeless tobacco use.

RÉSUMÉ La consommation de tabac sans fumée est courante en Asie du Sud. Outre les cancers de la cavité buccale et du pharynx, ses effets nocifs sont comparables à ceux de la consommation de tabac à fumer. Une enquête transversale à partir d'un échantillonnage systématique (n = 2030) a été menée en 2010 et 2011 afin d'évaluer la consommation de tabac sans fumée dans une population semi-urbaine et pluriethnique à Islamabad (Pakistan). La prévalence de la consommation de tabac sans fumée était de 16,0 % (21,6 % chez les hommes et 8,8 % chez les femmes) ; 51,7 % des consommateurs de tabac sans fumée étaient aussi des fumeurs de cigarettes. Le pourcentage de consommation de tabac sans fumée était comparativement élevé chez les hommes pachtounes (38,2 %) et les femmes sindhies (22,4 %). Les associations entre la consommation de tabac sans fumée, le groupe ethnique, la tranche d'âge, le niveau de revenu et la consommation de cigarettes étaient statistiquement significatives chez les consommateurs de tabac sans fumée de sexe masculin. Au sein de l'échantillon, 41,4 % (840/2030) possédaient des connaissances insuffisantes sur les problèmes de santé liés au tabac sans fumée. Des interventions appropriées sont nécessaires pour sensibiliser aux risques sanitaires et prévenir la consommation de tabac sans fumée.

Metal-ion directed synthesis of N2O2 type chelate complexes of Ni(II), Cu(II) and Zn(II): spectral, thermal and single crystal studies.

A set of Ni(II), Cu(II) and Zn(II) complexes of Schiff base have been synthesized by one pot condensation reaction of 2-hydroxy-4-methoxybenzophenone with 1,3-diaminopropane in 1:2:1 molar ratio. They have been characterized by elemental analysis, conductance measurement, thermal analysis (TGA/DTA), FT-IR, (1)H-NMR, EPR spectra, ESI-MS and electronic spectral studies. In order to establish the geometry, a single crystal X-ray structure for [Ni(L)] complex was determined. It crystallizes in monoclinic system having unit cell parameters a=14.015(5)Å, b=13.391(5)Å, c=14.931(5)Å and α=90.000(5)(o), ß=112.237(5)(o), γ=90.000(5)(o) with P 2(1)/c space group. No π-π stacking interaction was obtained in molecular packing diagram. A square-planar geometry has been confirmed for Ni(II) complex. Furthermore, on the basis of elemental analysis, IR, UV-visible and EPR data a square-planar geometry for Cu(II) and a distorted octahedral geometry for the Zn(II) complex has been established. In case of Zn(II) complex NO(3)(-) group was found to be coordinated in monodentate fashion. The low molar conductivity values of the complexes measured in chloroform and DMSO suggest their non-ionic nature.

Resonance Rayleigh scattering, second-order scattering and frequency doubling scattering spectra of copper(II)-Flutamide system with anionic surfactants and its analytical application.

A simple, sensitive, and rapid method based on ion association, for the determination of FLD has been developed. Flutamide (FLD) can react with Cu(II) to form 1:1 cationic chelate at pH 2.2-7.0 Mclivaine buffer medium, which can further react with anionic surfactants (AS) such as sodium dodecyl sulfate (SDS), sodium lauryl sulfonate (SLS) and sodium dodecylbenzene sulfonate (SDBS) to form 1:1 ion-association complexes. As a result, the resonance Rayleigh scattering (RRS), second-order scattering (SOS) and frequency doubling scattering (FDS) were enhanced to the highest degree. The maximum RRS, SOS and FDS wavelengths of three ion-association complexes were located at 345/345 nm, 610/305 nm and 430/860 nm, respectively. The increments of scattering intensity (ΔI) were directly proportional to the concentration of FLD in certain ranges. The detection limits (3σ) of FLD for SDS, SLS and SDBS systems were 1.9 ng ml(-1), 2.1 ng ml(-1) and 2.2 ng ml(-1)(RRS method), 2.4 ng ml(-1), 2.7 ng ml(-1) and 2.6 ng ml(-1) (SOS method) and 2.3 ng ml(-1), 2.4 ng ml(-1) and 2.5 ng ml(-1) (FDS method), separately. The sensitivity of RRS method was higher than those of FDS and SOS methods. The optimum conditions of RRS method and the influence factors, the composition and the reaction mechanism have been discussed. Since the method is highly selective, it does not interference concomitant substances. These methods were applied successfully for the determination of FLD in pharmaceutical formulation and urine samples.

Smoke-free homes: an intervention to reduce second-hand smoke exposure in households.

BACKGROUND: Second-hand tobacco smoke is a serious health hazard. We tested the fidelity and feasibility of the Smoke-Free Homes (SFH) intervention and looked for preliminary evidence of its effectiveness in imposing smoking restrictions in homes in Pakistan. METHODS: SFH was piloted and adapted for Pakistan. The adapted SFH intervention was then delivered to primary schoolchildren, community leaders and health professionals in a semi-rural Union Council. We carried out a survey before and after the intervention to assess adult smoking behaviour and restrictions at homes. We also carried out focus group discussions with stakeholders to determine the appropriateness and acceptability of the intervention. RESULTS: We found the adapted SFH intervention feasible and appropriate in a typical semi-rural setting in Pakistan. The proportion of smoke-free homes increased from 43% (95%CI 37.4-48.2) to 85% (95%CI 80.9-89.2) after the intervention. The number of households with at least one smoker decreased from 57.5% (95%CI 52.1-62.9) to 38.4% (95%CI 32.7-44.1). There was a reduction in self-reported adult smoking prevalence from 44% (95%CI 39-48) to 28% (95%CI 24-33) in males. CONCLUSION: SFH has the potential to influence adult smoking behaviour in households. This approach needs to be further evaluated to establish its effectiveness and cost-effectiveness and to ascertain its long-term sustainability.

Synthesis, spectroscopic, magnetic and thermal properties of bimetallic salts, [Ni(L)][MCl4] [where M=Co(II), Zn(II), Hg(II) and L=3,7-bis(2-aminoethyl)-1,3,5,7-tetraazabicyclo(3.3.1)nonane]. X-ray structure of [Ni(L)][CoCl4].

New bimetallic complex salts corresponding to the formulation [Ni(L)][MCl(4)] have been synthesized by the facile reaction between [Ni(L)](ClO(4))(2) and [MCl(2)(PPh(3))(2)] in high yields [where M=Co(II), Zn(II), Hg(II) and L=3,7-bis(2-aminoethyl)-1,3,5,7-tetraazabicyclo(3.3.1)nonane]. The complexes were characterized by IR, electronic spectra, TGA/DSC, magnetic moment and conductivity measurements. The X-ray crystal structure for [Ni(L)][CoCl(4)] clearly establishes the cationic-anionic interaction. It crystallizes in the space group P1 with unit cell dimensions a=7.1740(15)A, b=8.1583(16)A and c=8.3102(16)A. A square-planar geometry is evident for the [Ni(L)](2+) cation while the anion is found to be tetrahedral. A two-step thermolytic pattern is observed in the pyrolysis of the bimetallic complex salts.

Interaction of organotin with piperazine derived self-assembled cylindrical bisdithiocarbamates: spectral and thermal investigations.

Few organotin complexes of the type R4Sn2L2 where R=CH3 (2), C4H9 (3), C6H5 (4), and Sn2L2Cl4 (5) (L=bis(2,2'-dithiopiperazinato-2,2'-diaminodiethylamine)) have been synthesized and suitably characterized by FT-IR, UV-vis, 1H NMR, 119Sn NMR, ESI-MS, TGA/DSC, microanalysis and room temperature molar conductivity data. On the basis of FT-IR spectral studies, a symmetrical bidentate coordination has been proposed for all the complexes while the absence of any higher peak in the ESI-MS may be corroborated with the formation of binuclear complexes. On the basis of 119Sn NMR spectroscopy, six-coordinate geometry has been observed for the Sn-center in all the complexes. The TGA/DSC profile of the complexes implies their higher stability than its precursor. However, on the basis of IDT values the stability order of the organotin complexes was found to be 4>3>2. The room temperature conductivity values of the 1 mM solution of the ligand and its complexes are found to be comparable with that of non-ionic complexes.

Synthesis and characterization of transition metal 2,6-pyridinedicarboxylic acid derivatives, interactions of Cu(II) and Ni(II) complexes with DNA in vitro.

Mononuclear complexes M(L)Cl(2) where M=Mn(II), Fe(II), Co(II), Ni(II) and Cu(II) and (L=N,N-diethylpiperazinyl,2,6-pyridinedicarboxylate), have been synthesized and characterized by elemental analysis, FT-IR, (1)H NMR spectroscopy, UV-vis, magnetic moment, TGA/DSC, cyclic voltammetry and conductivity measurement data. The spectral data suggests that the dipicolinic acid acts as a bidentate ligand and is coordinated to the metal ion through the carboxylate oxygen. The cyclic voltammogram for Cu(L)Cl(2) complex was found to display two reversible Cu(II)/Cu(I) and Cu(II)/Cu(III) redox couple. The ligand exhibits a two-step thermolytic pattern while the complexes decompose in three stages respectively. An octahedral geometry has been proposed for both the complexes. The investigation of the interaction of the complexes with calf thymus DNA has been performed with absorption spectroscopy and fluorescence quenching experiments, which showed that the complexes are avid binders of calf thymus DNA. Also the interaction of the Cu(II) and Ni(II) complexes with plasmid DNA (pUC 19) was studied using agarose gel electrophoresis. The results revealed that these complexes can act as effective DNA cleaving agents resulting in the nicked form of DNA (pUC 19) under physiological conditions. The gel was run both in the absence and presence of an oxidizing agent (H(2)O(2)). The ligand and its complexes have also been screened against microbes in order to study their antibacterial action. The results revealed that the Cu(II) complex has activity comparable with the reference drugs gentamycin and flucanzole.

Mathematical methods for diffusion MRI processing.

In this article, we review recent mathematical models and computational methods for the processing of diffusion Magnetic Resonance Images, including state-of-the-art reconstruction of diffusion models, cerebral white matter connectivity analysis, and segmentation techniques. We focus on Diffusion Tensor Images (DTI) and Q-Ball Images (QBI).

Validation of vessel-based registration for correction of brain shift.

The displacement and deformation of brain tissue is a major source of error in image-guided neurosurgery systems. We have designed and implemented a method to detect and correct brain shift using pre-operative MR images and intraoperative Doppler ultrasound data and present its validation with both real and simulated data. The algorithm uses segmented vessels from both modalities, and estimates the deformation using a modified version of the iterative closest point (ICP) algorithm. We use the least trimmed squares (LTS) to reduce the number of outliers in the point matching procedure. These points are used to drive a thin-plate spline transform to achieve non-linear registration. Validation was completed in two parts. First, the technique was tested and validated using realistic simulations where the results were compared to the known deformation. The registration technique recovered 75% of the deformation in the region of interest accounting for deformations as large as 20 mm. Second, we performed a PVA-cryogel phantom study where both MR and ultrasound images of the phantom were obtained for three different deformations. The registration results based on MR data were used as a gold standard to evaluate the performance of the ultrasound based registration. On average, deformations of 7.5 mm magnitude were corrected to within 1.6 mm for the ultrasound based registration and 1.07 mm for the MR based registration.